Catalyst activator

ABSTRACT

A two component catalyst activator comprises:  
     1) a Lewis acidic organoboron (or an orgonoaluminum) component; and  
     2) a component defined by the formula AOSO 2 R wherein A is a pseudo cationic group and R is a hydrocarbyl or substituted hydrocarbyl. The catalyst activator is used in combination with a transition metal catalyst for the polymerization of olefins. The catalyst activator provides improved catalyst activities. It is especially useful in solution polymerizations because of desirable solubility characteristics in comparison to the borate salts used in prior activators.

FIELD OF THE INVENTION

[0001] This invention relates to a two component activator for apolymerization catalyst.

BACKGROUND OF THE INVENTION

[0002] This invention relates to catalyst activation for olefinpolymerizations.

[0003] It is now well known to use an aluminoxane, especially amethylaluminoxane, to activate olefin polymerization catalystscontaining group 3-10 metal complexes (particularly those metalcomplexes which contain delocalized pi ligands and are known as“metallocene catalysts”).

[0004] It is also known to use organoboron activators for olefinpolymerization catalysts. Tris (pentafluorophenyl) borane, and nearderivatives thereof, are particularly well known in this regard. Saltsof tetrakis (pentafluorophenyl) boron are similarly employed. The tris(pentafluorophenyl) borane activators are desirable for use in solutionpolymerization (because of their excellent solubility). The borate saltsgenerally offer higher polymerization activities but are difficult touse in solution polymerizations because of their low solubilities in nonpolar solvents.

[0005] In addition, all of the aforementioned activators are expensive.

[0006] Accordingly, it would be desirable to improve the performance ofprior art activators, especially with respect to lowering the cost ofthe activators and improving the solubility of highly active boronactivators for solution polymerizations.

SUMMARY OF THE INVENTION

[0007] The present invention provides a catalyst activator comprising:

[0008] 1) a Lewis acid component defined by the formula ML₁L₂L₃ whereinM is boron or aluminum; each of L₁, L₂ and L₃ is independently selectedfrom the group consisting of hydrocarbyl, substituted hydrocarbyl,hydrocarboxylide and substituted hydrocarboxylide; and L₃ is selectedfrom the group consisting of hydrocarbyl, substituted hydrocarbyl,hydrocarboxylide, substituted hydrocarboxylide, amino, phosphido,siloxy, sulfido and halide; and

[0009] 2) a second component defined by the formula AOSO₂R where A is apseudo cationic group and R is hydrocarbyl or substituted hydrocarbyl.

[0010] The activator of this invention is particularly useful for thepolymerization of addition polymerizable monomers (especiallymonoolefins) in the presence of a transition metal catalyst. Catalystsbased on group 4 metals are preferred. Thus, another embodiment of thisinvention provides a catalyst system comprising:

[0011] 1) a catalyst activator as above; and

[0012] 2) a catalyst comprising a group 3-10 metal complex.

[0013] A third embodiment of this invention provides a process for thepolymerization of olefins.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0014] The activator of this invention comprises two essentialcomponents which are described in detail below.

[0015] ML₁L₂L₃ or Lewis Acid Component

[0016] The first activator component (also referred to herein as a LewisAcid) is defined by the formula:

ML₁L₂L₃

[0017] wherein M is a metal selected from the group consisting of boronand aluminum; and ligands L₁ and L₂ are each (independently) hydrocarbyl(optionally substituted) or hydrocarboxylide (optionally substituted).The hydrocarbyl groups have from 1 to 30 carbon atoms and may be linear,branched, cyclic or aromatic. The hydrocarbyl groups may also besubstituted. By way of non-limiting example, the substituents may behalide, hydrocarbyl, amino or phosphino groups.

[0018] The term hydrocarboxylide as used herein is meant to itsconventional meaning, namely that there is an oxygen atom between M andthe remaining of the ligand fragment. For clarity, this may beillustrated by the formula:

M-O—R

[0019] wherein M is as defined above and R is a hydrocarbyl group(optionally substituted) as described above.

[0020] Two or more of the ligands L₁, L₂ and L₃ may optionally bebridged so as to form a bidentate ligand. L₃ is a ligand which may be ahydrocarbyl (optionally substituted), hydrocarboxylide (optionally)substituted—both as described directly above, halide, amino, phosphido,siloxy or sulfido.

[0021] Preferred activator components of the formula ML₁L₂L₃ are tri(fluoro-hydrocarbyl) boranes and aluminum alkyls. It is preferred thataluminum alkyl (if employed) is present as a constituent of analuminoxane mixture, as will be illustrated in the examples. Tri(isobutyl) aluminum (TIBAL) may also be employed.

[0022] It is especially preferred to use a fluoro substituted tri(hydrocarbyl) borane, particularly tris (pentafluorophenyl) borane forsolution polymerizations.

[0023] 2. Ionic Component

[0024] The second essential activator component is defined by theformula:

AOSO₂R

[0025] wherein A is a pseudo cationic group and R is hydrocarbyl orsubstituted hydrocarbyl.

[0026] A highly preferred second component is Ph₃COSO₂CF₃ where each Phis a phenyl group.

[0027] Whilst not wishing to be bound by theory, it is believed thatcomponents defined by the formula AOSO₂R should not be referred to assalts. For example, Ph₃COSO₂CF₃ decomposes in water to trityl alcoholand triflic acid (instead of the [Ph₃C⁺][OSO₂CF⁻ ₃]) which would beexpected if Ph₃COSO₂CF₃ was a true salt).

[0028] However, for convenience, the group A is referred to herein as apseudo cationic group (i.e. as if AOSO₂R were a salt).

[0029] Using the nomenclature which is typically used to describe salts,it is preferred that A be selected from the group consisting ofcarbenium, ammonium, oxonium, silylium, phosphonium and sulfonium. Morecorrectly, A may be defined as preferably being R′₃C (instead of [R′₃C⁺]for carbenium); R′₄N (instead of (R′N)⁺ for ammonium); R′3O (instead of[R′₃O]⁺ for oxonium; R′3Si (instead of [R′₃ Si]⁺ for silylium; R′4P(instead of [R′₄P]⁺ for phosphonium); and R′3S (instead of [R′3S]⁺ forsulfonium)—where R′ in all of the formulae in this sentence refers to ahydrocarbyl or substituted hydrocarbyl group.

[0030] It is highly preferred that the pseudo cationic group A be R′₃Cor R′₄N.

[0031] The R group in formula AOSO₂R is a hydrocarbyl having from 1 to20 carbon atoms. It is preferably halo substituted and is mostpreferably CF₃.

[0032] Thus, the most preferred second component is Ph₃COSO₂CF₃ whereeach Ph is phenyl. Ph₃COSO₂CF₃ presently has a Chemical Abstract (CA)index name of methanesulfonic acid trifluorotriphenylmethylester (orMSATFTPME). A search of Chemical Abstracts shows that MSATFTPME is aknown substance and has been reported to be useful in 1) the preparationof coatings (Japanese Patent 2954442 B2, issued Sep. 27, 1999 from KokaiJP 06267911); 2) the preparation of oxy-amino sugars (ref: JapaneseKokai JP 06056868 A2, dated Mar. 1, 1994); and 3) the preparation ofX-ray masks (ref: Japanese Kokai JP 062627830 A2, dated Sep. 22, 1994).

[0033] In general, the amount of second component (i.e. AOSO₂R) which isused in the activators of this invention is from about 0.5 to 5.0 molesper mole of the metal M (i.e. boron or aluminum) contained in the threecoordinate Lewis acid component. The second component is preferably usedin an approximately equimolar amount with the metal M. However, thesecond component may be used in excess (especially when a boroncontaining Lewis acid is used in a solution polymerization) or the metalM may be in excess (especially when an aluminum alkyl is used as theLewis acid component).

[0034] The two components may be added separately (or alternativelytogether) to the polymerization reaction. Another alternative is toco-support the two components on a polymerization catalyst support foruse in a slurry or gas phase polymerization (as well be illustrated inthe Examples).

[0035] A. Supported and Unsupported

[0036] The activator of this invention may be used in a supported formor in an unsupported form.

[0037] It is particularly preferred to use the catalyst activator ofthis invention in un-supported form in a solution polymerizationprocess. When doing so, it is especially preferred to use a tri(fluorosubstituted aryl) borane as the aforedefined ML₁L₂L₃ component.Examples of such boranes include monoalkyl bis (fluorophenyl) borane anddialkyl mono (pentafluorophenyl) borane. The most preferred borane istris (pentafluorophenyl) borane. The preferred second component for usewith these boranes is Ph₃OSO₂CF₃.

[0038] The activator produced from these two components is extremelyactive, as will be illustrated in the examples. In addition, the twocomponents have good solubility in the solvents which are typically usedin a solution polymerization process.

[0039] Thus, the activator of this invention has significant advantagesin comparison to the known fluoroboranes (such as B(C₆F₅)₃) or saltsthereof (such as [Ph₃C][B(C₆F₅)₄], trityl borate) when used in asolution polymerization process. Most notably the boranes (such asB(C₆F₅)₃) are convenient to use because of high solubility but oftenprovide comparatively low catalyst productivity in comparison to theanalogous salts (such as trityl borate). The two components activatorsof the present invention have very good solubility characteristics andfurther provide a highly productive catalyst activation.

[0040] It is preferred to use a “supported” form of the presentactivator when a slurry or gas phase polymerization process is used.Techniques to prepare supported catalysts are well known to thoseskilled in the art. In general, the activator and catalyst are depositedupon a particulate support which may be (for example) prepared from ametal oxide or polymeric material. Metal oxides are preferred.

[0041] The use of metal oxide supports in the preparation of olefinpolymerization catalysts is known to those skilled in the art. Anexemplary list of suitable metal oxides includes oxides of aluminum,silicon, zirconium, zinc and titanium. Alumina, silica andsilica-alumina are metal oxides which are well known for use in olefinpolymerization catalysts and are preferred for reasons of cost andconvenience. Silica is particularly preferred.

[0042] It is preferred that the metal oxide have a particle size of fromabout 1 to about 200 microns. It is especially preferred that theparticle size be between about 30 and 100 microns if the catalyst is tobe used in a gas phase or slurry polymerization process and that asmaller particle size (less than 10 microns) be used if the catalyst isused in a solution polymerization.

[0043] Conventional porous metal oxides which have comparatively highsurface areas (greater than 1 m²/g, particularly greater than 100 m²/g,more particularly greater than 200 m²/g) are preferred to non-porousmetal oxides.

[0044] Conventional calcining conditions may be employed—i.e. calciningtemperatures of from about 150° C. to about 900° C. for periods of timeranging from about 10 minutes to about 48 hours. Preferred calciningconditions include temperatures of from 200° C. to 700° C. for times offrom 1 to 8 hours.

[0045] It is preferred to use an aluminum alkyl as the essential ML₁L₂L₃component of this invention when the activator is used in supportedform. It is particularly preferred to provide the aluminum alkyl as aconstituent of an aluminoxane. Many conventional (and commerciallyavailable) aluminoxanes contain from 5 to 30 mole % aluminum alkyl(expressed as the molar percentage of aluminum which is present asaluminum alkyl divided by the total molar quantity of aluminum in thealuminoxane).

[0046] Aluminoxanes are readily available items of commerce which areknown to be cocatalysts for olefin polymerization catalyst (especiallygroup 4 metal metallocene catalysts). A generally accepted formula torepresent aluminoxanes is:

(R)₂AlO(RAlO)_(m)Al(R)₂

[0047] wherein each R is independently an alkyl group having from 1 to 6carbon atoms and m is between 0 and about 50. The preferred aluminoxaneis methylaluminoxane wherein R is predominantly methyl. Commerciallyavailable methylaluminoxane (“MAO”) and “modified MAO” are preferred foruse in this invention. [Note: In modified MAO, the R groups of the aboveformula are predominantly methyl but a small fraction of the R groupsare higher hydrocarbyls—such as ethyl or butyl—so as to improve thesolubility of the “modified MAO” in aliphatic solvents.]

[0048] The metal oxide and aluminoxane are contacted together preferablyusing conventional techniques such as mixing the aluminoxane and metaloxide together in a linear or aromatic hydrocarbon (such as hexane ortoluene) at a temperature of from 10 to 200° C. for a time if from oneminute to several hours). The amount of aluminoxane (based on thecombined weight of the aluminoxane and the metal oxide).

[0049] The resulting activator is suitable for use in olefinpolymerization reactions when combined with a polymerization catalyst.Any polymerization catalyst, which is activated by an aluminoxane or aborane or boron activator, may be employed. Preferred catalysts includeolefin polymerization catalysts which contain group 4 metals (such asTi, Hf or Zr), group 5 metals (especially V), Fe, Ni, Cr and Pd. Highlypreferred catalysts contain a group 4 metals and at least onedelocalized, pi-bonded ligand. It is especially preferred to provide anAl:Me mole ratio of from 10:1 to 200:1, especially 50:1 to 150:1 in thefinished, supported catalyst complex (where Al is the aluminum providedby the aluminoxane and Me is the group 4 metal). The catalyst supportcontaining the aluminoxane may be co-supported with the polymerizationcatalyst using techniques which are conventionally used to preparesupported aluminoxane/metallocene catalysts. Such techniques are wellknown to those skilled in the art. In general, a hydrocarbon slurry ofthe catalyst component may be contacted with the catalyst complex. It ispreferred to use a hydrocarbon in which the catalyst complex is soluble.The examples illustrate suitable techniques to prepare the “catalystsystems” of this invention.

[0050] Particularly preferred catalysts are group 4 metal catalystsdefined by the formula:

[0051] wherein M_(e) is selected from titanium, hafnium and zirconium;each L′₃ is an activatable ligand; L′₁ and L′₂ are independentlyselected from the group consisting of cyclopentadienyl, substitutedcyclopentadienyl (including indenyl and fluorenyl) and heteroatomligands, with the proviso that L′₁ and L′₂ may optionally be bridgedtogether so as to form a bidentate ligand. It is further preferred thatn=2 (i.e. that there are 2 monoanionic activatable ligands).

[0052] As previously noted, each of L′₁ and L′₂ may independently be acyclopentadienyl ligand or a heteroatom ligand. Preferred catalystsinclude metallocenes (where both L′₁ and L′₂ are cyclopentadienylligands which may be substituted and/or bridged) andmonocyclopentadienyl heteroatom catalysts (especially a catalyst havinga cyclopentadienyl ligand and a phosphinimine ligand), as illustrated inthe Examples. Brief descriptions of exemplary ligands are providedbelow.

[0053] Cyclopentadienyl Ligands

[0054] L′₁ and L′₂ may each independently be a cyclopentadienyl ligand.As used herein, the term cyclopentadienyl ligand is meant to convey itsbroad meaning, namely a substituted or unsubstituted ligand having afive carbon ring which is bonded to the metal via eta-5 bonding. Thus,the term cyclopentadienyl includes unsubstituted cyclopentadienyl,substituted cyclopentadienyl, unsubstituted indenyl, substitutedindenyl, unsubstituted fluorenyl and substituted fluorenyl. An exemplarylist of substituents for a cyclopentadienyl ligand includes the groupconsisting of C₁₋₁₀ aryl or aryloxy radical; an amido radical which isunsubstituted or substituted by up to two C₁₋₈ alkyl radicals; aphosphido radical which is unsubstituted or substituted by up to twoC₁₋₈ alkyl radicals; silyl radicals of the formula —Si—(R¹)₃ whereineach R¹ is independently selected from the group consisting of hydrogen,a C₁₋₈ alkyl or alkoxy radical C₆₋₁₀ aryl or aryloxy radicals; germanylradicals of the formula Ge—(R¹)₃ wherein R¹ is as defined directlyabove.

[0055] Activatable Ligand

[0056] Each L′₃ is an activatable ligand. The term “activatable ligand”refers to a ligand which may be activated by a cocatalyst or “activator”(e.g. the aluminoxane) to facilitate olefin polymerization. Exemplaryactivatable ligands are independently selected from the group consistingof a hydrogen atom, a halogen atom, a C₁₋₁₀ hydrocarbyl radical, a C₁₋₁₀aryl or aryloxy radical, an amido radical which is unsubstituted orsubstituted by up to two C₁₋₈ alkyl radicals; a phosphido radical whichis unsubstituted or substituted by up to two C₁₋₈ alkyl radicals.

[0057] The number of activatable ligands depends upon the valency of themetal and the valency of the activatable ligand. As previously noted,the preferred catalysts contain a group 4 metal in the highest oxidationstate (i.e. 4+) and the preferred activatable ligands are monoanionic(such as a halide—especially chloride, or an alkyl—especially methyl).Thus the preferred catalyst contains two activatable ligands. In someinstances, the metal of the catalyst component may not be in the highestoxidation state. For example, a titanium (III) component would containonly one activatable ligand. Also, it is permitted to use a dianionicactivatable ligand although this is not preferred.

[0058] Heteroatom Ligands

[0059] As used herein, the term heteroatom ligand refers to a ligandwhich contains a heteroatom selected from the group consisting ofnitrogen, boron, oxygen, phosphorus and sulfur. The ligand may be sigmaor pi bonded to the metal. Exemplary heteroatom ligands includephosphinimine ligands, ketimide ligands, siloxy ligands amido ligands,alkoxy ligands, boron heterocyclic ligands and phosphole ligands. Briefdescriptions of such ligands follow:

[0060] Phosphinimine Ligand

[0061] Phosphinimine ligands are defined by the formula:

[0062] wherein each R¹ is independently selected from the groupconsisting of a hydrogen atom, a halogen atom, a C₁₋₈ alkoxy radical,one C₆₋₁₀ aryl or aryloxy radical, an amido radical, a silyl radical ofthe formula:

—Si—(R ²)₃

[0063] wherein each R² is independently selected from the groupconsisting of hydrogen, a C₁₋₈ alkyl or alkoxy radical, C₆₋₁₀ aryl oraryloxy radicals, and a germanyl radical of the formula:

Ge—(R²)₃

[0064] wherein each R² is independently selected from the groupconsisting of hydrogen, a C₁₋₈ alkyl or alkoxy radical, C₆₋₁₀ aryl oraryloxy radicals, and a germanyl radical of the formula:

Ge—(R²)₃

[0065] wherein each R² is as defined above.

[0066] The preferred phosphinimines are those in which each R¹ is ahydrocarbyl radical. A particularly preferred phosphinimine istri-(tertiary butyl) phosphinimine (i.e. where each R¹ is a tertiarybutyl group).

[0067] Ketimide Ligands

[0068] As used herein, the term “ketimide ligand” refers to a ligandwhich:

[0069] a) is bonded to the group 4 metal via a metal-nitrogen atom bond;

[0070] b) has a single substituent on the nitrogen atom, (where thissingle substituent is a carbon atom which is doubly bonded to the Natom); and

[0071] c) has two substituents (Sub 1 and Sub 2, described below) whichare bonded to the carbon atom.

[0072] Conditions a, b and c are illustrated below:

[0073] The substituents “Sub 1 ” and “Sub 2” may be the same ordifferent. The substituents may be bonded together—i.e. it ispermissible to include a bond which bridges Sub 1 and Sub 2. Exemplarysubstituents include hydrocarbyls having from 1 to 20 carbon atoms,silyl groups, amido groups and phosphido groups. For reasons of cost andconvenience it is preferred that these substituents both behydrocarbyls, especially simple alkyls and most preferably tertiarybutyl.

[0074] Siloxy Heteroligands

[0075] These ligands are defined by the formula:

—(μ)SiR_(x)R_(y)R_(z)

[0076] where the — denotes a bond to the transition metal and μ issulfur or oxygen.

[0077] The substituents on the Si atom, namely R_(x), R_(y) or R_(z) isnot especially important to the success of this invention. It ispreferred that each of R_(x), R_(y) and R_(z) is a C₁₋₄ hydrocarbylgroup such as methyl, ethyl, isopropyl or tertiary butyl (simply becausesuch materials are readily synthesized from commercially availablematerials).

[0078] Amido Ligands

[0079] The term “amido” is meant to convey its broad, conventionalmeaning, Thus, these ligands are characterized by (a) a metal-nitrogenbond; and (b) the presence of two substituents (which are typicallysimply alkyl or silyl groups) on the nitrogen atom.

[0080] Alkoxy Ligands

[0081] The term “alkoxy” is also intended to convey its conventionalmeaning. Thus these ligands are characterized by (a) a metal oxygenbond; and (b) the presence of a hydrocarbyl group bonded to the oxygenatom. The hydrocarbyl group may be a ring structure and/or substituted(e.g. 2, 6 di-tertiary butyl phenoxy).

[0082] Boron Heterocyclic Ligands

[0083] These ligands are characterized by the presence of a boron atomin a closed ring ligand. This definition includes heterocyclic ligandswhich also contain a nitrogen atom in the ring. These ligands are wellknown to those skilled in the art of olefin polymerization and are fullydescribed in the literature (see, for example U.S. Pat. Nos. 5,637,659;5,554,775 and the references cited therein).

[0084] Phosphole Ligands

[0085] The term “phosphole” is also meant to convey its conventionalmeaning. “Phosphole” is also meant to convey its conventional meaning.“Phospholes” are cyclic dienyl structures having four carbon atoms andone phosphorus atom in the closed ring. The simplest phosphole is C₄PH₄(which is analogous to cyclopentadiene with one carbon in the ring beingreplaced by phosphorus). The phosphole ligands may be substituted with,for example, C₁₋₂₀ hydrocarbyl radicals (which may, optionally, containhalogen substituents), phosphido radicals, amido radicals, silyl oralkoxy radicals.

[0086] Phosphole ligands are also well known to those skilled in the artof olefin polymerization and are described as such in U.S. Pat. No.5,431,116 (Sone to Tosoh).

[0087] Polymerization Processes

[0088] This invention is suitable for use in any conventional olefinpolymerization process, such as the so-called “gas phase”, “slurry”,“high pressure” or “solution” polymerization processes. Polyethylene,polypropylene and ethylene propylene elastomers are examples of olefinpolymers which may be produced according to this invention.

[0089] The preferred polymerization process according to this inventionuses ethylene and may include other monomers which are copolymerizabletherewith such as other alpha olefins (having from three to ten carbonatoms, preferably butene, hexene or octene) and, under certainconditions, dienes such as hexadiene isomers, vinyl aromatic monomerssuch as styrene or cyclic olefin monomers such as norbornene.

[0090] The present invention may also be used to prepare elastomeric co-and terpolymers of ethylene, propylene and optionally one or more dienemonomers. Generally, such elastomeric polymers will contain about 50 toabout 75 weight % ethylene, preferably about 50 to 60 weight % ethyleneand correspondingly from 50 to 25% of propylene. A portion of themonomers, typically the propylene monomer, may be replaced by aconjugated diolefin. The diolefin may be present in amounts of up to 10weight % of the polymer although typically is present in amounts fromabout 3 to 5 weight %. The resulting polymer may have a compositioncomprising from 40 to 75 weight % of ethylene, from 50 to 15 weight %propylene and up to 10 weight % of a diene monomer to provide 100 weight% of the polymer. Preferred but not limiting examples of the dienes aredicyclopentadiene, 1,4-hexadiene, 5-methylene-2-norbornene,5-ethylidene-2-norbornene and 5-vinyl-2-norbornene. Particularlypreferred dienes are 5-ethylidene-2-norbornene and 1,4-hexadiene.

[0091] The polyethylene polymers which may be prepared in accordancewith the present invention typically comprise not less than 60,preferably not less than 70 weight % of ethylene and the balance one oremore C₄₋₁₀ alpha olefins, preferably selected from the group consistingof 1-butene, 1-hexene and 1-octene. The polyethylene prepared inaccordance with the present invention might also be useful to preparepolyethylene having a density below 0.910 g/cc—the so-called very lowand ultra low density polyethylenes.

[0092] The supported form of the catalyst system of this invention ispreferably used in a slurry polymerization process or a gas phasepolymerization process.

[0093] The typical slurry polymerization process uses total reactorpressures of up to about 50 bars and reactor temperature of up to about200° C. The process employs a liquid medium (e.g. an aromatic such astoluene or an alkane such as hexane, propane or isobutane) in which thepolymerization takes place. This results in a suspension of solidpolymer particles in the medium. Loop reactors are widely used in slurryprocesses. Detailed descriptions of slurry polymerization processes arewidely reported in the open and patent literature.

[0094] In general, a fluidized bed gas phase polymerization reactoremploys a “bed” of polymer and catalyst which is fluidized by a flow ofmonomer which is at least partially gaseous. Heat is generated by theenthalpy of polymerization of the monomer is then re-circulated throughthe polymerization zone together with “make-up” monomer to replace thatwhich was polymerized on the previous pass. As will be appreciated bythose skilled in the art, the “fluidized” nature of the polymerizationbed helps to evenly distribute/mix the heat of reaction and therebyminimize the formation of localized temperature gradients (or “hotspots”). Nonetheless, it is essential that the heat of reaction beproperly removed so as to avoid softening or melting of the polymer (andthe resultant-and highly undesirable—“reactor chunks”). The obvious wayto maintain good mixing and cooling is to have a very high monomer flowthrough the bed. However, extremely high monomer flow causes undesirablepolymer entertainment.

[0095] An alternative (and preferable) approach to high monomer flow isthe use of an inert condensable fluid which will boil in the fluidizedbed (when exposed to the enthalpy of polymerization), then exit thefluidized bed as a gas, then come into contact with a cooling elementwhich condenses the inert fluid. The condensed, cooled fluid is thenreturned to the polymerization zone and the boiling/condensing cycle isrepeated.

[0096] The above-described use of a condensable fluid additive in a gasphase polymerization is often referred to by those skilled in the art as“condensed mode operation” and is described in additional detail in U.S.Pat. No. 4,543,399 and U.S. Pat. No. 5,352,749. As noted in the '399reference, it is permissible to use alkanes such as butane, pentanes orhexanes as the condensable fluid and amount of such condensed fluidpreferably does not exceed about 20 weight percent of the gas phase.

[0097] Other reaction conditions for the polymerization of ethylenewhich are reported in the '399 reference are:

[0098] Preferred Polymerization Temperatures: about 75° C. to about 115°C. (with the lower temperatures being preferred for lower meltingcopolymers—especially those having densities of less than 0.915 g/cc—andthe higher temperatures being preferred for higher density copolymersand homopolymers); and

[0099] Pressure: up to about 1000 psi (with a preferred range of fromabout 100 to 350 psi for olefin polymerization).

[0100] The '399 reference teaches that the fluidized bed process is welladapted for the preparation of polyethylene but further notes that othermonomers may be employed—as is the case in the polymerization process ofthis invention.

[0101] It is preferred to use tris (pentafluorophenyl) borane as theLewis acid (and Ph₃COSO₂CF₃ as the second activator component) incombination with a catalyst comprising a group 4 metal complex whenemploying solution polymerization conditions. The molar ratio of theboron to the group 4 metal is preferably from 0.5/1 to 5/1. Analuminoxane (especially MAO) may also be included in an amountsufficient to scavenge the polymerization medium of adventiousimpurities.

[0102] Highly preferred group 4 metal catalysts contain at least onedelocalized pi ligand (such as a cyclopentadienyl ligand which may besubstituted) and/or a phosphinimine ligand.

[0103] Solution processes for the copolymerization of ethylene and analpha olefin having from 3 to 12 carbon atoms are well known in the art.These processes are conducted in the presence of an inert hydrocarbonsolvent typically a C₅₋₁₂ hydrocarbon which may be unsubstituted orsubstituted by a C₁₋₄ alkyl group, such as pentane, methyl pentane,hexane, heptane, octane, cyclohexane, methylcyclohexane and hydrogenatednaphtha. An example of a suitable solvent which is commerciallyavailable is “Isopar E” (C₈₋₁₂ aliphatic solvent, Exxon Chemical Co.).

[0104] Preferred solution polymerization processes use at least twopolymerization reactors. The polymer solution exiting from the firstreactor is preferably transferred to the second polymerization (i.e. thereactors are most preferably arranged “in series” so that polymerizationin the second reactor occurs in the presence of the polymer solutionfrom the first reactor).

[0105] The polymerization temperature in the first reactor is from about80° C. to about 180° C. (preferably from about 120° C. to 160° C.) andthe second reactor is preferably operated at a higher temperature. Coldfeed (i.e. chilled solvent and/or monomer) may be added to both reactorsor to the first reactor only. The polymerization enthalpy heats thereactor. The polymerization solution which exits the reactor may be morethan 100° C. hotter than the reactor feed temperature. Thepolymerization reactor(s) are preferably “stirred reactors” (i.e. thereactors are extremely well mixed with a good agitation system).Agitation efficiency may be determined by measuring the reactortemperature at several different points. The largest temperaturedifference (i.e. between the hottest and coldest temperaturemeasurements) is described as the internal temperature gradient for thepolymerization reactor. A very well mixed polymerization reactor has amaximum internal temperature gradient of less than 10° C. A particularlypreferred agitator system is described in co-pending and commonlyassigned U.S. Pat. No. 6,024,483. Preferred pressures are from about 500psi to 8,000 psi. The most preferred reaction process is a “mediumpressure process”, which means that the pressure in each reactor ispreferably less than about 6,000 psi (about 42,000 kilopascals or kPa),and most preferably from about 1,500 psi to 3,000 psi (about14,000-22,000 kPa).

[0106] Suitable monomers for copolymerization with ethylene includeC₃₋₁₂ alpha olefins which are unsubstituted or substituted by up to twoC₁₋₆ alkyl radicals. Illustrative non-limiting examples of suchalpha-olefins are one or more of propylene, 1-butene, 1-pentene,1-hexene, 1-octene and 1-decene. Octene-1 is highly preferred.

[0107] The monomers are dissolved/dispersed in the solvent either priorto being fed to the first reactor (or for gaseous monomers the monomermay be fed to the reactor so that it will dissolve in the reactionmixture). Prior to mixing, the solvent and monomers are generallypurified to remove potential catalyst poisons such as water, oxygen orother polar impurities. The feedstock purification follows standardpractices in the art, e.g. molecular sieves, alumina beds and oxygenremoval catalysts are used for the purification of monomers. The solventitself as well (e.g. methyl pentane, cyclohexane, hexane or toluene) ispreferably treated in a similar manner. The feedstock may be heated orcooled prior to feeding to the first reactor. Additional monomers andsolvent may be added to the second reactor, and it may be heated orcooled.

[0108] Generally, the catalyst components may be premixed in the solventfor the reaction or fed as separate streams to each reactor. In someinstances premixing may be desirable to provide a reaction time for thecatalyst components prior to entering the reaction. Such an “in linemixing” technique is described the patent literature (most notably U.S.Pat. No. 5,589,555, issued Dec. 31, 1996 to DuPont Canada Inc.). Theresidence time in each reactor will depend on the design and thecapacity of the reactor. Generally the reactors should be operated underconditions to achieve a thorough mixing of the reactants. In addition,it is preferred (for dual reactor operations) that from 20 to 60 weight% of the final polymer is polymerized in the first reactor, with thebalance being polymerized in the second reactor. As previously noted,the polymerization reactors are preferably arranged in series (i.e. withthe solution from the first reactor being transferred to the secondreactor). In a highly preferred embodiment, the first polymerizationreactor has a smaller volume than the second polymerization reactor. Onleaving the reactor system the solvent is removed and the resultingpolymer is finished in a conventional manner.

[0109] Further details are provided by the following non-limitingexamples.

EXAMPLES

[0110] The invention will now be illustrated in further detail by way ofthe following non-limiting examples. For clarity, the examples have beendivided into two parts, namely Part A (Compound Synthesis) and Part B(Polymerization).

[0111] Gel permeation chromatography (“GPC”) analysis was carried outusing a commercially available chromatograph (sold under the name Waters150 GPC) using 1,2,4-trichlorobenzene as the mobile phase at 140° C. Thesamples were prepared by dissolving the polymer in the mobile phasesolvent in an external oven at 0.1% (weight/volume) and were run withoutfiltration. Molecular weights are expressed as polyethylene equivalentswith a relative standard deviation of 2.9% and 5.0% for the numberaverage molecular weight (Mn) and weight average molecular weight (Mw),respectively.

[0112] The following abbreviations are used in the Examples: ¹ H NMR =proton nuclear magnetic resonance ¹³ C NMR = carbon 13 nuclear magneticresonance Hr = hour Mw = weight average molecular weight Mn = numberaverage molecular weight PD = polydispersity (or Mw/Mn) PE =polyethylene PO = polyolefin t-Bu = tertiary butyl (e.g. ^(t)Bu₃ =tri-tertiary butyl) i-Pr = isopropyl Ph = phenyl Me = methyl THF =tetrahydrofuran MeOH = methanol TIBAL = triisobutylaluminum, purchasedfrom Akzo Nobel

[0113] Part A: Compound Synthesis

[0114] All the compounds were considered to be oxygen and moisturesensitive. Manipulations were therefore carried out under nitrogen usinga glovebox or under argon using Schenk techniques. Anhydrous toluene waspurchased from Aldrich and purified over conventional mole sieves.Methylaluminoxanes were purchased from Akzo-Nobel (MMAO-7) and Albemarle(AB-MAO). The MMAO-7 contained approximately 20-25% “free” trimethylaluminum (as determined by the vendor using a pyridine titrationtechnique).

[0115] A.2 Synthesis of Ph₃COSO₂CF₃

[0116] CH₂Cl₂ (50 mL) solution of Ph₃CCl (1.38 g, 4.96 mmol) was addedto a stirred CH₂Cl₂ (50 mL) slurry of AgSO₃CF₃ (1.28 g, 4.96 mmol)slowly at 0° C. The mixture was warmed up to room temperature andstirred for 12 hours. The precipitate was removed by a filtration. TheCH₂Cl₂ was evaporated under vacuum to dryness to give an orange solid(1.3 g, 67% Yield). 1H NMR (CDCl₃, δ): 7.4 (m, 9H), 7.6 (m, 6H). ¹⁹F NMR(CDCl₃, δ): −80.0 (s).

[0117] A.3 Synthesis of i-Pr₃SiOSO₂CF₃ Modified MMAO-7

[0118] i-Pr₃SiOSO₂CF₃ _(—) (539 mg, 1.761 mmol) was added slowly toMMAO-7 (9.797 g, 6.88% weight Al in heptane, Al:Si=14:1). The mixturewas stirred for 12 hours before used for olefin polymerization.

[0119] A.4 Synthesis of i-Pr₃SiOSO₂CF₃ Modified AB-MAO

[0120] i-Pr₃SiOSO₂CF₃ (777 mg, 2.578 mmol) was added slowly to AB-MAO(6.49 g, 4.51% weight Al in heptane, Al:Si=6:6). The mixture was stirredfor 12 hours before used for olefin polymerization.

[0121] A.5 Synthesis of Ph₃COSO₂CF₃ Modified AB-MAO

[0122] Ph₃COSO₂CF₃ (102 mg, 0.26 mmol) was added slowly to AB-MAO (10.00g, 4.51% weight Al in heptane, Al:Si=6:4). The mixture was stirred forone hour before used for olefin polymerization.

[0123] Part B: Polymerizations

[0124] Solution and Slurry Batch Reactor Results

[0125] All the polymerization experiments described below were conductedusing a 500 ml stainless steel autoclave. All the chemicals (solvent,catalyst and cocatalyst) were fed into the reactor batchwise exceptethylene which was fed on demand. No product was removed during thepolymerization reaction. The feed streams (ethylene, cyclohexane) werepurified prior to feeding into the reactor by contact with variousabsorption media to remove impurities such as water, oxygen, sulfur andpolar materials. All components were stored and manipulated under anatmosphere of purified argon or nitrogen. Ethylene polymerizations wereperformed in the reactor equipped with an air driven stirrer and anautomatic temperature control system. The polymerization reaction timeis 10 minutes for each experiment. The polymerization was terminated byadding 5 ml of methanol to the reactor and the polymer was recovered byevaporation of the solvent or by drying it under vacuum. Thepolymerization activities were calculated based on the weight of thepolymer produced. All reported pressures are gauge pressures.Triisobutylaluminum (TIBAL) was purchased from Aldrich and[CPh₃][B(C₆F₅)₄] was purchased from Asahi Glass Inc.

[0126] B.3 Polymerization with Ph₃COSO₂CF₃

[0127] Cyclohexane (300 mL) was transferred into the reactor with TIBAL(0.3 mmol). The solution was heated to 35° C. and saturated with 10pounds per square inch gauge (psig) of ethylene. A toluene solution of(t-Bu₃PN)CpTiMe₂ (0.00300 mmol) and a toluene mixture of Ph₃COSO₂CF₃(0.00315 mmol) and B(C₆F₅)₃ (0.00315 mmol) were injected into thereactor via syringes. Polymerization temperature increased to 48° C.After 10 minutes, polyethylene (10.6 g) was produced. Activity=21200gPE/mmol-Ti*hr.

[0128] B.4 Comparative Example with Ph₃C[B(C₆F₅)₄]

[0129] Cyclohexane (300 mL) was transferred into the reactor with TIBAL(0.3 mmol). The solution was heated to 35° C. and saturated with 10pounds per square inch gauge (psig) of ethylene. A toluene solution of(t-Bu₃PN)CpTiMe₂ (0.00300 mmol) and a toluene solution of Ph₃C[B(C₆F₅)₄](0.00315 mmol) was injected into the reactor via syringes.Polymerization temperature increased to 50° C. After 10 minutes,polyethylene (6.8 g) was produced. Polymerization activity is 13600gPE/mmol-Ti*hr.

[0130] B.5 Polymerization with i-Pr₃SiOSO₂CF₃ Modified MMAO-7

[0131] Cyclohexane (216 mL) and i-Pr₃SiOSO₂CF₃ modified MMAO-7 (5.368 g,6.52% weight Al) were transferred into the reactor. The solution washeated to 160° C. and saturated with 140 psig of ethylene and stirred at2000 rpm. A toluene solution of (t-Bu₃PN)CpTiCl₂ (17.2 mg, 0.04297 mmol)was injected into the reactor via syringes. Polymerization temperatureincreased to 167° C. and average polymerization temperature is 160.09°C. After 10 minutes, polyethylene (13 g) was produced. Polymerizationactivity is 1815.1 gPE/mmol-Ti*hr.

[0132] B.6 Comparative Example with MMAO-7

[0133] Cyclohexane (216 mL and MMAO-7 (2.55 g, 13.6% weight Al) weretransferred into the reactor. The solution was heated to 160° C. andsaturated with 140 psig of ethylene and stirred at 2000 rpm. A toluenesolution of (t-Bu₃PN)CpTiCl₂ (17.23 mg, 0.04305 mmol) was injected intothe reactor via syringes. Polymerization temperature increased to 167°C. and average polymerization temperature is 159.9° C. After 10 minutes,polyethylene (10.4 g) was produced. Polymerization activity is 1450gPE/mmol-Ti*hr.

[0134] Gas Phase Batch Reactor Results

[0135] Catalyst Preparation

[0136] Standard Schlenk and drybox techniques were used in thepreparation of supported catalyst systems using (t-Bu)₃PNTi(Cp)Cl₂ as acatalyst. Solvents were purchased as anhydrous materials and furthertreated to remove oxygen and polar impurities by contact with acombination of activated alumina, molecular sieves and copper oxide onsilica/alumina. Where appropriate, elemental compositions of thesupported catalysts were measured by Neutron Activation analysis and areported accuracy of +1% (weight basis).

[0137] The supported catalysts were prepared by supporting a MAOderivative obtained from Section A (A4, A5 or a commercially availableMAO from Albemarle) on a commercially available silica support (soldunder the trade-name “XPO 2408” by W. R. Grace), followed by depositionof the catalyst. The aiming point for the Al/Ti mole ratio was 120/1.

[0138] Polymerization

[0139] All the polymerization experiments described below were conductedusing a semi-batch, gas phase polymerization reactor of total internalvolume of 2.2 L. Ethylene gas was measured to the reactor on acontinuous basis using a calibrated thermal mass flow meter, followingpassage through purification media as described above. Reaction pressurewas set at 200 psig. A pre-determined mass of the supported catalystsample (Table 1) was added to the-reactor under the flow of the inletgas with no pre-contact of the catalyst with any reagent, such as acatalyst activator. The catalyst was activated in-situ (in thepolymerization reactor) at the reaction temperature in the presence ofthe monomers, using a metal alkyl complex which has been previouslyadded to the reactor to remove adventitious impurities. Purified andrigorously anhydrous sodium chloride (160 g) was used as acatalyst-dispersing agent. The internal reactor temperature was set at90° C. and monitored by a thermocouple in the polymerization medium andcontrolled to ±1.0° C. The duration of the polymerization experiment wasone hour. Following the completion of the polymerization experiment, thepolymer was separated from the sodium chloride and the yield wasdetermined. TABLE 1 Polymerization Data Supported PE Activity Catalyst¹Co-monomer Produced gPE/mmol- MAO (mg) (mL) (g) Ti.h.[C2] Example 1i-Pr₃SiOSO₂CF₃ 30 0 44.7 79854 modified AB-MAO Example 2 i-Pr₃SiOSO₂CF₃21 5 40.1 136505 modified AB-MAO Example 3 Ph₃COSO₂CF₃ 39 0 36.4 66752Modified AB-MAO Example 4 Ph₃COSO₂CF₃ 17 5 57.8 159458 Modified AB-MAOComparative AB-MAO 23 0 18.7 43574 Example

What is claimed is:
 1. A catalyst activator for olefin polymerizationcatalysis comprising: 1) a Lewis acid defined by the formula: ML₁L₂L₃ wherein M is a metal selected from the group consisting of boron andaluminum; each of L₁ and L₂ is independently selected from the groupsconsisting of hydrocarbyl, substituted hydrocarbyl, hydrocarboxylide andsubstituted hydrocarboxylide; and L₃ is selected from the groupconsisting of hydrocarbyl, substituted hydrocarbyl, hydrocarboxylide,substituted hydrocarboxylide, halide, amino, phosphido, siloxy andsulfido; and 2) a second component defined by the formula: AOSO₂R wherein A is a pseudo cationic group and R is selected from the groupconsisting of hydrocarbyl and substituted hydrocarbyl.
 2. A catalystactivator according to claim 1 wherein said metal M is boron.
 3. Thecatalyst activator according to claim 2 wherein each of L₁, L₂ and L₃ isa pentafluorophenyl ligand.
 4. The catalyst activator according to claim2 wherein said A is selected from the group consisting of R′₃C and R₄′Nwherein each R′ is independently selected from the group consisting ofhydrocarbyl and substituted hydrocarbyl.
 5. The catalyst activatoraccording to claim 4 wherein A is Ph₃C.
 6. The catalyst activatoraccording to claim 2 wherein said second component is Ph₃COSO₂CF₃. 7.The catalyst activator according to claim 1 comprising tris(pentafluorophenyl) borane and Ph₃COSO₂CF₃.
 8. The catalyst activatoraccording to claim 1 wherein said metal M is aluminum.
 9. The catalystactivator according to claim 8 wherein said ML₁L₂L₃ is a trialkylaluminum.
 10. The catalyst activator according to claim 9 wherein saidaluminum alkyl is associated with an aluminoxane.
 11. The catalystactivator according to claim 10 wherein said aluminum alkyl is trimethylaluminum and said aluminoxane is methylaluminoxane.
 12. The catalystactivator according to claim 11 wherein said A is Ph₃C.
 13. The catalystactivator according to claim 12 comprising: 1) trimethyl aluminum; and2) Ph₃COSO₂CF₃.
 14. A catalyst system for olefin polymerizationcomprising: A) a group 3-10 metal complex; and B) a catalyst activatorcomprising: 1) a Lewis acid defined by the formula: ML₁L₂L₃  wherein Mis a metal selected from the group consisting of boron and aluminum;each of L₁ and L₂ is independently selected from the groups consistingof hydrocarbyl, substituted hydrocarbyl, hydrocarboxylide andsubstituted hydrocarboxylide; and L₃ is selected from the groupconsisting of hydrocarbyl, substituted hydrocarbyl, hydrocarboxylide,substituted hydrocarboxylide, halide, amino, phosphido, siloxy andsulfido; and 2) a second component defined by the formula: AOSO₂R wherein A is a pseudo cationic group and R is selected from the groupconsisting of hydrocarbyl and substituted hydrocarbyl.
 15. The catalystsystem according to claim 14 wherein said metal is a group 4 metalselected from the group consisting of titanium, zirconium and hafnium.16. The catalyst system according to claim 15 wherein said metal complexcontains at least one de-localized pi bonded ligand.
 17. The catalystsystem according to claim 15 wherein said metal complex is defined bythe formula:

wherein M′_(e) is selected from titanium, hafnium and zirconium; eachL′₃ is an activatable ligand; L′₁ and L′₂ are independently selectedfrom the group consisting of cyclopentadienyl, substitutedcyclopentadienyl and heteroatom ligands, with the proviso that L′₁ andL′₂ may optionally be bridged together so as to form a bidentate ligand.18. A process for olefin polymerization comprising contacting thecatalyst system of claim 14 with at least one olefin underpolymerization conditions.
 19. The process of claim 18 wherein said atleast one olefin comprises ethylene.
 20. The process of claim 18 whereinsaid polymerization conditions consist of solution polymerizationconditions and said activator comprises: 1) tris (pentafluorophenyl)borane; and 2) Ph₃COSO₂CF₃.